This application claims the benefit of a priority under 35 USC 119 to French Patent Application No. 0005892 filed May 9, 2000, the entire contents of which are incorporated by reference.
The present invention relates to a belt tensioner having means for protecting against rupture or loosening or relaxation or breakage or stretching or layer separation or tooth tearing of the belt. Each of these belt conditions is an example of belt failure. In particular the present invention relates to a belt having an integrated safety device to protect belt failure.
Transmission or drive belts are used, for example, between a motor and the system driven by such motor when a direct drive proves to be impossible, for example for reasons of space, present problems of reliability. Systematic replacement of such belts after a predetermined period of operation only partially remedies these problems.
In some applications, from the viewpoint of safety, it is absolutely essential to prevent the consequences of such a failure of a transmission or drive belt. This is the case, for example, with a radiology apparatus such as a x-ray apparatus that may comprise a mobile or movable piece of equipment situated above the patient. The raising and lowering of the equipment may be controlled by means of a transmission or drive belt, where failure of the belt may cause falling of the mobile or movable equipment if the failure is not substantially instantaneously detected, with immediate and priority locking of the mobile or movable equipment.
In an embodiment of the present invention a belt tensioner comprises an integrated safety device substantially instantaneously detecting failure of the belt such that this information may be transmitted, for example, for the immediate and priority intervention to prevent any untoward consequence of such a failure.
In addition, an embodiment of the invention is a radiology apparatus, such as a x-ray apparatus, equipped with such a belt tensioner.
The belt tensioner in an embodiment of the invention comprises: a means for support; a roller; a means for carrying on which the roller is mounted for rotation and which is mounted on the support so that it can move back-and-forth between two extreme positions, means for urging the means for carrying from a first to a second of the two extreme positions, the means for urging being arranged between the support and the means for carrying, means for actuation by the means for carrying so as to occupy a first state only when the means for carrying is at the first extreme position and to switch to the second state as soon as or when the means for carrying has left this first extreme position under the action of the means for urging, the means for actuation being mounted on the support, and means for mounting the support on a base, in a fixed position in relation to the belt to be tensioned, so that the means for carrying occupies the first extreme position only when the belt is intact and has a predetermined tension.